For patients receiving enzyme-inducing AEDs but not valproate:
Initial dose: 50 mg orally once a day for 2 weeks, then increase to 50 mg orally twice a day for 2 weeks.
Maintenance dose: 150 to 250 mg orally twice a day.
Dose may be increased by 100 mg/day every week.
Maintenance doses as high as 700 mg/day have been used.

Escalation regimen for lamotrigine extended release:
For use in Primary Generalized Tonic-Clonic and Partial Onset Seizures

Treatment with lamotrigine is introduced based on concurrent medications.

Dose increases at week 8 or later should not exceed 100 mg daily at weekly intervals.

As other drugs are subsequently introduced or withdrawn, the dose of lamotrigine may need to be adjusted.

Conversion from adjunctive therapy to monotherapy with lamotrigine extended-release:

The goal of the transition regimen is to attempt to maintain seizure control while mitigating the risk of serious rash associated with the rapid titration of lamotrigine extended-release.

The recommended maintenance dosage range of lamotrigine extended-release as monotherapy is 250 to 300 mg given once daily. The recommended initial dose and subsequent dose escalations for lamotrigine extended-release should not be exceeded.

Conversion from adjunctive therapy with carbamazepine, phenytoin, phenobarbital, or primidone to monotherapy with lamotrigine extended-release: After achieving a dosage of 500 mg/day the concomitant enzyme-inducing AED should be withdrawn by 20% decrements each week over a 4-week period. Two weeks after completion of withdrawal of the enzyme-inducing AED, the dosage of lamotrigine extended-release should be decreased no faster than 100 mg/day each week to achieve the monotherapy maintenance dosage range of 250 to 300 mg/day.

As other drugs are subsequently introduced or withdrawn, the dose of lamotrigine may need to be adjusted.

Usual Pediatric Dose for Seizure Prophylaxis

Dosage depends on patient's concomitant medications (i.e., valproic acid, enzyme-inducing AEDs specifically phenytoin, phenobarbital, carbamazepine, and primidone), or AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproic aced. Patients receiving concomitant rifampin or other drugs that induce lamotrigine glucuronidation and increase clearance should follow the same dosing regimen as that used with anticonvulsants that have this effect (e.g., phenytoin, phenobarbital, carbamazepine, and primidone).

Added to an antiepileptic drug regimen therapy:
Children 2 to 12 years: Immediate release formulation: (only whole tablets should be used for dosing): children 2 to 6 years will likely require maintenance doses in the higher end of recommended range; patients weighing less than 30 kg may need as much as a 50% increase in maintenance dose, compared with patients weighing greater than 30 kg; titrate dose to clinical effect.

Renal Dose Adjustments

Use with caution and consider lower maintenance doses on patients with renal dysfunction.

Liver Dose Adjustments

No dosage adjustments are needed in patients with mild hepatic dysfunction. Initial, escalation, and maintenance doses should generally be reduced by approximately 25% in patients with moderate and severe hepatic dysfunction without ascites and 50% in patients with severe liver impairment with ascites. Escalation and maintenance doses may be adjusted according to clinical response.

Dose Adjustments

The smallest available strength of lamotrigine chewable dispersible tablets is 2 mg, and only whole tablets should be administered. If the calculated dose cannot be achieved using whole tablets, the dose should be rounded down to the nearest whole tablet.

If the decision is made to restart a patient who has discontinued lamotrigine, the need to restart with the initial dosing recommendations should be assessed. The greater the interval of time since the previous dose, the greater consideration should be given to restarting with the initial dosing recommendations. If a patient has discontinued lamotrigine for a period of more than five half-lives, it is recommended that initial dosing recommendations and guidelines be followed. (Please note that the half-life of lamotrigine is affected by concomitant medications).

Discontinuing therapy: Children and Adults: Do not rapidly discontinue; when discontinuing lamotrigine therapy, gradually decrease the dose by about 50% per week and taper over at least 2 weeks unless safety concerns require a more rapid withdrawal. Note: If discontinuing other anticonvulsants and maintaining lamotrigine therapy, keep in mind that discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs, such as rifampin, that induce lamotrigine glucuronidation should be expected to prolong the half-life of lamotrigine; discontinuing valproic acid should shorten the half-life of lamotrigine; monitor patient closely; dosage change may be needed.

Dialysis

Lamotrigine is removed an average of 20% in 4 hours of hemodialysis.

Other Comments

When discontinuing therapy, a stepwise reduction of dose over at least two weeks is recommended unless safety concerns require a more rapid withdrawal.

Lamotrigine extended-release should not be chewed, crushed, or divided.

If discontinuing other anticonvulsants and maintaining lamotrigine therapy, it should be noted that discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs, such as rifampin, that induce lamotrigine glucuronidation should prolong the half-life of lamotrigine. Discontinuing valproic acid should shorten the half-life of lamotrigine. The patient should be closely monitored for any necessary dose changes.

Chewable Dispersible Tablets:
Lamotrigine chewable dispersible tablets may be swallowed whole, chewed, or dispersed in water or diluted fruit juice. If the tablets are chewed, a small amount of water or diluted fruit juice should also be consumed to aid in swallowing. To disperse lamotrigine chewable dispersible tablets, add the tablets to a small amount of liquid (one teaspoon, or enough to cover the medication). Approximately one minute later, when the tablets are completely dispersed, swirl the solution and consume the entire quantity immediately. No attempt should be made to administer partial quantities of the dispersed tablets.

Orally Disintegrating Tablets (ODT):
Lamotrigine orally disintegrating tablets should be placed onto the tongue and moved around in the mouth. The tablet will disintegrate rapidly, can be swallowed with or without water, and can be taken with or without food.

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